Self-locking threaded device



Jan. 16, 1945. c, w SQLDAN I I SELE-LOCKINGTHREADED DEVICE Filed Oct.25, 1944 5 Sheets-Sheet 1 Jan. 16, 1945.

C. W. SOLDAN CKING THREAiDED DEV SELF-LO Filed 001:. '25, 1944 sSheets-Sheet s Jan. 1945. c w; SQLDAN 2,367,379

' SELF-LOCKING THREADED DEVICE Filed Oct. 25, 1944- g 5 Sheets-Sheet 476 (Inf/veg I z I Clqzpnce W'qlilan,

mwiz vm Y Jan. 16, 1945. v c. w. SOLDAN I 2,367,379

SELF-LOCKING THREADED DEVICE Filed Oct. 25 1944' 5 Sheets-Sheet 5ClmwnceWSpldan panion threaded elementf a .line I'lll of .Figure 6; I IFigure 11 is a greatly enlarged v'ievv showing an 1 I assembled floatingthread member and cap screw, 56'

Patented Jim-7161 1.9-4.5-

UNITED ,smes I PATENT OFFICE 2,367,379 I V I SELF-LOCKING THREADEDDEVICE Clarence W. Soldan, Baltimore, ,Md., assignor to Crown Cork '&Seal Compan lnc 'Baltimore, Md., a corporation of New York ApplicationOctober 25, 1944, Serial No. 5 0,221

26- Claims.

the cap screw. being indicated in dot and dash.

lines; I

Figure 12 is a view of the floating thread mem- 4 her of Figure 11 asviewed from th direction indistruction that when they are used withcompanion threaded elements, neither element can movewith respect to theother due to vibration.

Another object of the invention vis. to provide sat-locking threadedelements of such design that they can be readily assembled and threadedinto companion elements. r

Other objects and advantages of the invention will beapparent from thefollowing specification and accompanying drawings ,wherein:-

Figure 1 is an elevation. of a capscrew constructed in accordance Withthe present inven-. tion;

Figure 2 is a view showing the leading end of the Figure 1 cap screw inside elevation, a floating thread member included in the presentinvention being omitted from the view;

Figure 3 is Figure 2;

Figure 4 is a transverse section ion the lined-4 ofFigure2;- II

Figure 5 is an endview oi the cap screw of Figure 2, the view beingtaken from .the right of Figure 2; I

an axial section onthe line 3-3 of Q a modified form of floating threadmember, the

I capfscrew being indicated in dot and dash lines.

cated by the arrow a in Figure 1-1;

Figure 13 is a side view of the floating thread element viewed from thedirection indicated by the arrow b of Figure 11;

'Figure 14 is a radial sectional view of the floating thread 'member;

Figure 15 is a. side elevation of a cap screw or modified form; r

Fi re 16 is a'trans floating thread member shown in Figure l'ljandFigure 171s a greatly enlarged view showing the modified cap screw ofFigure ldassembled with Referring to Figures 1 to 14, the numeral I 20designates a cap screw constructed-in accordance with the presentinvention, the cap screw being provided with an [American Nationalcoarse thread indicated atz.

v National Bureau of Standards Handbook H28..

' shallbe hereafter knownas the American National thread;

Figure '6 is aview showing" the cap screw and l j floating thread memberin side elevation and.

Figure 6a is a transverse section on the line 6a- 6a of Figure 6i IFigure 7 is a view similar to Figure 6 but showing the cap screw 'fully'threaded into the com- Figure 7ais a transverse sectional view on theline la-1a of Figure 7; I I Figure 8 is a view. similar to Figure 6-butshowing the cap screw being unthreaded from the companion element;

Figure 8a is .a transverse tic-8a of Figure 8; I I I Figure '9 is anend" view of'the leading end of the section on the As shown-best inFigure g2, the leading end of the cap screw has a portion of the threadsre-.

moved therefrom as indicated at 3,- with the result:

that the thread bf'the cap screw begins at the point 4 which is spacedfrom the point at which the thread would normally begin on such a capscrew. T he leng'th of, thread 5 beginning at point I dis of'extrem'elyshort extent-and terminates in a concave abutment in stem axiallyextending.

groove 6. Beyondgroove 6, one helixor the thread 2 is entirely omittedand, instead, a helical groove 6 is substantially semi-circular intransverse section, the 'curvature ,or radius of the g'roove-beingoian-outline hereinafter discussed. However, asshcwn iii-Figure 4, themaximum cap-screw with. the floating threaded member applied thereto inthe position illustrated in Figure 6?? I Figure 10 is atransversesectional view onthe depth of the axial groove firalong a'line extendingdiametrically of the screw, is the sameas the substantiallycorresponding to the height to which the threads 2 extend abovetherootdiamv verse section of the modifiedconcave curve.

eter 9. The bottom wall l6 of the helical groove 1 isconcentric with theaxis of the cap screw, except as hereinafter described.

The helical groov I must be regarded as extending into axial groove 6 inthat the end III of thread 5 on one wall of the axial groove forms anabutment at the leading end of the helical groove.

Also, the end ll of the thread 2 beginning oppo site the wall of axialgroove 6 forms the trailing end of helical groove I in that it forms anabutment at the trailing end of the helical groove.

Asbest shown in Figure 4, the helical groove 1 includes a restriction 20in the form of a radial projection or enlargement on its bottom wall 16.

The restriction 20 includes an outer or top surface 2 I concentric withthe axis of thecap screw which, in a .75" cap screw, for example, wouldextend approximately 25. An incline 22' also forming part of therestriction joins the bottom or inner wall it of helical groove Ito thesurface 2| of the restriction. Inclined surface 22 is-prefscrew so thatthe incline will be a relativelyfiat It' will be noted that the incline22 forms the leading sid of the restriction 20 and that the trailingside of the restriction is formed by the axial'groove-i.

As best shown in Figure .4, the diameter on which the surface 2| ofrestriction 20 is formed is less than the root or minor diameter 9 ofthewalls 21, the band is provided with a thread 28 of the-samecross-sectional conformation as the erably formed by a'radius basedoutside the cap mum of .75".

threads 2 of the cap screw I. While member 2'5 is of generally helicalform, it is not of uniform diameter throughout its length. For example,as clearly indicated in Figure 11, both ends 29 and threads 2 of the capscrew 7 when moved in the opposite direction, the leading end-29 ofmember 25 will come into abutment with the end ill of the short lengthof thread 5. Before the trailing end 30 of member 25 can contact withthe leading 'end ll of the threads], it must move over the restriction20. 7

For the purpose of setting forth the general form of a typicalself-locking element of the present invention, it may be pointed outthat a .75" American National coarse thread cap screw constructed inaccordance with the present invention to have a Class 2 fit, will havethe base wan 16 of its helical groove I formed on a radius of .249",while the surface 2| of restriction 20 will be formed on a radius of.285". In accordance with standards specified in said Handbook H28, theminor diameter of the screw I, i. e., its dsia ineter at the root 9 ofthe threads would be 2 3". I

It is to be noted that a .75" American National coarse thread cap screwdesigned to have a No. 2 fit with a female element may have the majordiameter of its threads a minimum M17372",

i. 'e.; a radius of .3686", as indicated in Figure 11 of the presentapplication. The female or nut element to be used with such a' screwwould have the root or major diameter of its threads 9. mini- In otherwords, with a No. 2 fit, and with the screw of minimum tolerance majordiameter, the companion elements would have a diametrical play of.0128".

The member 25 to-be used with a .75" Ameriecan National coarse-threadscrew such as indi cated by the numeral I would beof a radial thicknessof .0929" as indicated in Figure 14. Figure 11' gives radial dimensionsfor a member 25 provided for use with such a .75" coarse threaded capscrew having a No. 2 fit. It will be noted from this figure that themember 25 is symmetrical in that the two halves thereof on 0D- positesides of the diametrically extending lines C-C are identical inconfiguration. More particularly, within each of the arcs G, whichcomprise the central portion of member 25 and extend for substantially90 in each direction from the righhhand end of the line 0-0 in Figure 30are bent ordeflected inwardly-irom'a helix so that the innermost pointof each end is closer to thediametricaliy opposed point on the surface26 than'is the case with any other two diametrically opposed points onthe inner surface 25.

The member 25 is formed of spring steel to be bodily resilient, thoughit has sufiicient rigidity to exert strong pressure against any efiortto bend it inwardly from the normal form illustrated in Figure 11 and,when bent inwardly, will exert considerable force outwardly.

' Figures 6 and 6a show the band 25 fitted in the helical groove of thecap screw I, and it will'be noted that the end 29 forms the leadingend'of the band wane the opposite end an forms its trailing end. Thediameter of the inner surface 25 of-the member 25' is suflicientlylarger than the diameter ofthe surface l5 of groove 1 that memher 25 maymove diametrically and circumferentially in the groove 1 when not withina com-'- panion threaded element. Because of this, the

member 25 can be regarded as a floating thread onelement 2 as referredto above. with regard to circumferential movement of member 25 in' thegroove 1, it will be clear-from Figures 6a to 8a that member 25 can onlymove clockwise in these figures to such-extent that its trailing end 30will abut against the leading endll of the 11, themember 25 has anoutside radius of .3839" and an inside radius of .291". Then,

throughout the arcs H extending for 44, the out- ;side radius is formedon a curvature of .367

centered on the lines G which form. the outer limits of the arcs G. Fromthe lines .H' defining the ends of the arcs H, the outside radius ofmember 25 is formed on a curvatl'lre of 3 based on each lineI-I'. Byreason of the above-described inward deflection of member 25 adjacentits ends, its inside radius adjacenteach line H' will approximate .285",i. e., the radius of restriction 20 of screw I. The purpose of this ishereinafter described.

As is clear from Figures 4 and 5, the axial groove 6 is curved intransverse section and Figure ll shows the radius which may be used forthis curvature. By having groove 6 concavely curved, instead of withstraight side walls, it

can be formed by a single millingoperation. In

be noted that the member 25, throughout the ,as a symmetricallydistorted helix, or a two, arcs G, is normallyfof greater outside radiusthan the radius of the root or major diameter of a companion femalethreaded member to .receive screw I That is, throughout the 180 ofmember. 1

25 encompassed in the arcs G, member 25 is of a bar is of .375" radius.

.3839" outside radius, whereas the motor major a diameter of a companionfemale threaded meme Figure 11-clearly indicates that member 25,. whenunrestricted, has-an,

outside radius throughout the major portion of its length which isgreater than the major radius of the threads of screw I. a It will alsobe observed "the member 25 might be described as a'helix which isflattened along a line extending between 3 its two ends, as is the casewith the line 0-0.

Stated another way, member 25 may be described helix having its ends'bent inwardly.

The manner in which the floating thread member" 25 of Figures 1"to 14performs a'locking funcand 6a show the threaded element! being initiallythreaded-into -a machine body or' base 35 pro As shown in Figure 6a, thescrew I, being righthanded, .wilhrotate in the direction of the arrow ofFigure 6a, thereby rotating and moving to the right as indicated bythebent arrow of Figure'6. Before the member 25 is engaged with the threads36, its trailing portion 3|] should be positioned in contact with theleading end II of the' Under these circumstances, the 'resiliency'of thef om Figure 11 that.

Even extreme vibration will not cause member I to unthread'with respecttothe threads 3'.i because any unthreading rotation of screw I from theposition shown in Figures '7, 7a, and 11 (and, clgckwise with respect,to those 'flgures) 1; will simply cause the restriction 20 atthetrailingend ofgroove I to move into closer contact or engagement with thesurface3|. of member 25. Such movement'would have the effect of bending theinwardlyv curved trailing end 30 outwardly from the position shown andthis could not be accomplished by vibration alone.

, If it is desired to remove the cap screw I from the element 35, awrench of the usual form and size is applied to the cap screw and, uponthe application of strong force to the wrench, the cap screw may bereversely rotated in the direction tion in cooperation with the screw Iand a com panion threaded member is as follows: Figures 6 ,v-ided withAmerican National coarse threads 36.

member 25 will enable it to contract somewhat.

Generally speaking, this contraction will occur by inwardspringing ofthe member 25 throughout allof the portion thereof other than the end 30and the portion adjacent that end which is lying upon the restriction 20as indicated in Fig- -"ure'11'. -This inwardspringing will cause end 29to move slightly counter-cl'ockwisein groove 1 as' viewedin Figure 11and may even result in bend- I ing end 29 outwardly,- thereby increasingthe tension exerted on threaded element 35..

of the arrows of Figures 8 and 8a. The operation of the member 25 underthese conditions is as follows: Because of its bodilyresiliency andtendency to expand so that the greater portion of its length will be oflarger outside radius than the diameter of-the threads 36 of companionelement 35, member 25-will be prevented from ro-.'

However, with thetating in the element as. proper force applied, themember 25 will bend adjacent itsendf portion 30 so that the restriction2llwill' move beneath the surface 3|. When the inner tip 32 bears uponthe surface 20, the cap screw can then be turned to move the end 30 offrestriction 20 so that the screw I will occupy the position with.respect to member 25illustrated i in Figure 8a. In this position, theopposite end 29 of member 25 willlie in the axial groove Ii to abutagainst the surface ID of the groove so that the member 25 must thenunthread with element I. While the 'oversized dimensions and resiliencyof member 25 will still cause it to exert a strong drag against thethreads 36 during unthreading rotation of the cap screw in the directionof the arrows of Figures 8 and 8a, the cap screw can be unthreadedwiththe application of proper force to thewrench. 1

Because of the fact that the member 25 of Figures 1 to 14 isofsymmetrical form, it is immate-,

rial which endof member25 is positioned as the leading en d129 when itis placed upon a screw I This saves time in the assembly of the floating1thread member upon screw I. 60

3 at 'the end of a cap screw enables the floating thread member to beplaced inthe helical groove I when the member.2-5 is sprung open for as-Figures 7 and ia. show the cap screw- I fully threadedinto the element35, and it will be observed that the member 25 still occupies theposition relative to screw I which-is illustrated in The provision of anunthreaded area such as sembly; Because of the force rewired to springthe floating thread member open, it is impossible for the memberto fallfrom the element I or even be removed except by special tools.Therefore,

Figure 6a because threading rbtati'on of screw I. I

keeps shoulder I I in contact with the end surface of end 30 of band 25.l r

The strong force exerted outwardly against prevent member 25 ,fromhaving'unthreading movement with respect'to the threads 365 Hence, u if screw1 is to turn in the direction of the arrow designated fTounthread" inFigure ll it must turn relative to the member 25. lnotherpwords,

yibrationcannot cause member 25 to turn with element I .in -anunthreading direction. Infact,

member 25-is, in effect, a permanent part of the 'screw' I.

'- It will also be observed that because the restriction 20 is alwaysclosely adjacent the inthe threads 36 'by reason of the fact that member25 is normally oversiz'ed with respect thereto throughout the greaterportionof its" length will markedfTounthread in Figurell mustbring Imember 25 and'elementfll can only turn together in-an uhthreadingdirection under the conditions described belbw and involving the.application of extremelystrong turning force to the element I.'

wardly formed surface 3I at the trailing end 30 of mmber 25, there canbe a minimum of turning movement of screw I with respect to member 25under'vibration. That' is,fthe slightest movement of screw Lin thedirection of the arrow the restrictioni'llintoeven closer contact withthe inwardly curved surface 3|. Therefore, whenever a screw has beenmoved to the desired position, it can have no play in eitherdirection, 1. e., it.isflrmly locked against further possibility ofmovement as soon .as t "reading move-. ment by the operator has stopped.

. In order to enable the floating thread member ber 25 too sharplyduring assembly with the cap screw.

It has been found that an important reason With the above definition inmind. the character P in Figure 11 designates a point on the pitchdiameter of the cap screw I as well as the companion threaded element ornut 35. The character P25 in Figure 11 designates a point on thepitchdiameter of the portion of floating threaded element 25 which iswithin an arc G and, therefore, has both a larger outside diameter (orradius) and a larger pitch diameter than that inwhy a floating threadedmember such as disclosed herein and in said Harding application resistsmovement from a locked position such as shown, for example, in Figure11, is the following: when an unthreading tendency is initiated, eitherby vibration or by intent of an operator, the resultant movement of alocking end such as 3| with respect to a restriction such as imparts aforce to the member whereby the latter tends to straighten outthroughout its entire length. As a result, a tremendous outward andradial pressure is applied by the member 25 to the threads of thecompanion element 35. This force is greatly augmented throughout theportions 01 member 25 which have a diiferent, viz., larger, radius thanthat of the female element 35, as is the case with the portions ofmember 25 embraced by the arcs G in Figure 11.

I have found that the force exerted by the portions within the arcs G isso great that the size of the member 25 can be reduced according tovarious procedures hereinafter discussed, and that the resistance tounthreading movement will still be so high that it will be adequate tomeet foutside diameter which is greater than the outside or majordiameter of cap screw I. It has also been pointed out that when member25 is not within a female threaded element 35, the outside diameter ofportions of member 25 is normal- 1y larger than the root or majordiameter of a female threaded element 35, In short, the floatingthreaded element 25 of Figures '1 to 14 as hereinbefore described may betermed oversized in that portions thereofnormally have .an out-- sidediameter which is larger than the major diameters of the threadedelements I and 35. Obviously, the portions of member .25 which areoversized in outside diameter are also oversized with respect to pitchdiameter.

In connection with the above use of .the term pitch diameter, referenceis made to the definition of the pitch diameter ofa straight screwthreadwhich appears on page 2' of the abovementioned Handbook H28, whichdefinition reads as follows: .Pitch diameter-On a straight screw thread,the diameter of an' imaginary cylinder, the surface of which would passthrough the threads at such points as to make equal the width dicated byP. It will be observed that since point P25 is spaced a greater distancefrom the axis of cap screw I than point P, the pitch diameter (orradius) of the portion of member 25 within arc G is larger than thepitch diameter or radius of the cap screw I and element 35.

. It also will be observed that, according to the abovedefinition, athread may'be truncated in section, and thereby have a broader crest,without its pitch diameter being reduced.

I have found that in numerous instances it is only necessary that thepitch diameter of portions of member 25lbe larger than the pitchdiameter of screw I and female threaded element 35, and that so long asthis relationship is retained, the outside diameter of member 25 may bereduced. The dotted lines 25a superimposed on the floating thread member25 of Figures 11 and 14 indicate how this member might be of smalleroutside diameter'so long as the pitch diameter indicated by P25 ofportions thereof is greater than the pitch diameter P of elements I and35.

It will be observed thatmaking the line 25a the outer perimeterof member25 simply means that the depth of the thread on 25 is decreased and thatno other dimension of member 25 is thereby changed. In other words theportions of the tapered side walls of member 25 shown below line 25ainFigure 14 will still hear on the female thread of element 35 with thesame force such portions exert if the member 25 has a thread of standarddepth. I

With the outside diameter of the floating thread member 25 reduced'toconform to line 25a as described above, that is, if throughout itsperimeter, member 25 is smaller than the major diameter of either screwI or element 35, an adequate locking effect will still be obtained ifportions of. member 25 have their pitch diameter (or radius) largenthanthe pitch diameter of elements I and 35. -11 member 25 formed in thismanner has the advantage that it can be more readily threaded into afemale threaded element 35. Nevertheless, as indicated above, itstapered side walls embraced within the arcs G in Figure 11 includeentirely adequate surface to exert and maintain thenecessary pressureupon the opposed tapered walls of the thread of female element 35 whenmember 25 has a straightening-out tendency applied thereto ashereinbefore explained;

'Another'way in which the oversized floating thread member 25 of Figures1 to 14 can be reduced in outside diameter or radius is by reducing itsinside diameter or radius and, at the same time, maintaining its sectionsubstantially the same as shown in solid lines in Figure 14.

A member 25 having the last-mentioned characof the threads and the widthof the spaces cut by the surface of the cylinder.-

of the companion element.

gaging portion atits trailing end and alsohav- 14, the outside radiusthroughout the arcs G will I be. approximately .373". Therefore, thegreatest outside diameter (along lines G'G in Figure H) will beapproximately .746" instead of .766"

The oversized" floating thread member: 25

disclosed in Figures 1 to'14, i. e., the form where J trated thereinhas, its leading end formed'in a Y 1065 spring steel, or even greaterhardness, it is preferable .t'ohave the outside diameter of the lessthan the outside diameter of the, screw as above described. Also, inorder to meet actual working conditions, it is frequently desirable touse an undersized washer because of the follow.- ing circumstances.stated, a .75 American. Nationalcoarse thread capscrew designedto'ha'vea Class 2 fit with a female element is'finished to make theminimum major or outside diameter of its threads .7372".

However,--'t he maximum outside or major diameter of the cap screwthreads which is permitted is .75. On the other'hand, the female elementto be used with such a screw may have a mini ing the helical groovebfthe capscrew provided with a restriction at its trailing end. 7Referring to Figure 15, the capscrew 50 illusmanner generally similar tothat of the form hereinbefore described, except that the axial groove 5Ihas-a flat surface 52 extending parallel to a diameter 'of the capscrew. Also, the inner end 53 of groove 5| may be rounded. A, groove ofthis conformation can be formed by cutting a single milling operation.

The dimensions of the cap screw 50 are hereinafter set forth connection.with the description of the floating threaded member to be usedtherewith.

Figure 16 is a cross-sectional view of the floating thread member 54designed for use with cap screw 50, the dimensions being thoseintendedmember.25, throughout the length of the washer,

As has been hereinbeforefor use with a .75" American National coarsethread cap screw designed to have a Class 2 flt with a female element.As shown in Figure 16,

member 54 would have a thickness of .083"

thereby being narrower than the width of the helical groove 55, whichis,\ .1".. Theinclined or, threaded portion'of member 54 has its wallsof v the same tapered conformation as a thread of mum thread base ormajor diameter approximating .750 inch If a screw of maximum diam eteris used-with a floating thread'member of the oversized. type,anextremely tight flt with the female elementfwill result. Therefore,it"is frequently desirable to use a floating thread member of theundersized type. However, in some situations, for example, when it isassured that there will be a diametric play of- ;013 inch between thescrew. and the female element, .an oversized floating thread member isentirely practicable. i

It maybe stated at this point that the matter of. whether an undersizedor oversized floating thread member is used does not affect the lockingdiameter reduced to the line 25a in Figures 11 and 14, but its pitchdiameter 'and'inside radii kept the same as illustrated in Figure '11.That is, whenany unthrea'ding tendency is applied, the floating thread.member tends to straighten out, thereby exerting force against thefemale member.

the threaded element with which itis to be used. The width of the flatouter portion or. crest would be .018". Therefore, thread member 54 istruncated to have a different widthof crest from a standard threadsection, which latter would be .0125".

Figure 1'7 shows the floating thread member '54 of Figures '1-5 to 1'7mounted upona cap screw 50, the cap screw .being illustrated in dot anddash-lines. The base wall or inner wall 55 ofhelical groove 56' of' cap'screw would be .25"

in radius throughout the larger portion of its length. This groove wouldbe a true helix as is the case with the corresponding groove of- Figures1 to 14,. At its leading end 51, helical groove I axial groove 5|, thelatter groove being positioned M4" from the axis of the cap screw andhaving,

a width vof The trailing end 58 of helical groove 56 is provided with arestriction 59 formed on a radius of .281", this restriction terminatingcharacteristics of the member for the same reasons as have been statedabove in connection with the use of amember having its outside at itstrailing end at-the' flat inner wall of the axial groove 5|. 59 includesanjinclinedwall 60 which blends into 56 would merge into the flat innerwall 52 of the The leading side of restriction the .25" radius of themajor portionof the base I wall 55-of helical groove 58. f

Figure 17 shows the flat trailing end portion 61. of floating threadmember 54 positioned in the axial groove 5| of the cap screw, as' wouldbe the case when the cap screw'isbeing threaded An advantage of havinthe washer undersized is that once it'has been moved to the un-i-ilocked position, it can be readily unthreaded because it exerts nomarked drag upon the threads Figures 15 to 17 disclose an-undersizedfloatin thread member of a third type. In addition, the' ber 54 would be/64" or .266".

above, the radial thickness of member 54 is .087", its outside radiusthroughout arc'K would be structure shown in Figures 15 to 17' includesa [non-symmetrical floating thread. member and also may have a straighttrailing end'instead of a curved trailing end as indicated at 30 in theform of Figures 1'to'14. However, the structure hereinafter described inconnection with Figures 15 to 1'? has thecharacteristic common to theform of Figures 1 to 14 of having .thefloating into a female elementor-isin locked position 1 Member 54 has the tip of its' flat or lookingend 6| positioned A" from the tip of the therein.

leading, end. 62 and throughout an arc extendingapp'roximately 110therefrom,'. and indicated.

by the arcuate line K, the inside radius of mem- V endof arc K to line Lpositioned at the begin.-

thread member provided with a restriction en,-

ning of-the flat portion 6|, the inside radius of member 54 is 3%" or.281. Therefore, the outside radius of the arcuate portion designated bythe line L is .368".

Because the maximum major diameter of a /4" American National coarsethread cap-screw designed for a Class 2 fit is .'75,-or' .375'! radius,whereas the portion of member 54 indicated by Since, as stated From theradial line K designating the.

will be observed that this portion of member 54 is of smaller radiusthan the outside or major radius of the cap screw on which it is to beused. With .regard to the remaining curved portion of member 54, l. e.,that portion indicated by the arc L, this has an outside radius of .368"and, therefore, is only slightly undersized. However, as shown inFigurel'l, the diameter of member 54 taken along a line passing throughits leading -end 60 is approximately .721. Since-this diameter is amaximum diameter it will be clear that the maximum outside diameterofmember 54 under normal conditions will be less than the maximummajondiameter of' .75"' of the cap screw under discussion. The dimensionbetween portion, as well as a portion bent inwardly out of the helix,just as is true of the corresponding curved end portion of the floatingthread members of Figures 1 to 14.

With the device of Figs. 15 to 17 in the locked position indicated inFigure 17, i. e., with the flat 2,867,379 arc K has an outside radius ofonly .353",-it

another way, the length of member 54 measured ina circumferentialdirection, is not highly critical. The fact that a critical toleranceneed not be maintained at this point is advantageous because such atolerancewould be difficult to maintain. 'Also, in the manufacture ofthe cap screw, the critical tolerances are only those within the areaoccupied by axially extending groove 5 I. and

' restriction 59. These tolerances can readily be controlled duringmanufacture.

' The devices of the present invention obviously require no specialtools to operate them to locked position or to assist in unlocking. Inaddition, there are no parts which can deteriorate, as ocours withlooking devices formed of compressible material and, in use, thefloating thread is entire 1y enclosed so that it cannot be tamperedwith. The floating thread members are also of such design that theycannot becomebroken during operation and cannot mar the threads of acompanion elem'ent.

It will be understood that the dimensions of I the .75 cap screws of thepresent invention set forth hereinare merel to disclose the dimensurfaceat its trailing end 6| bearingagainst flat that direction, whether theforce be applied by.

an operator or by vibration, will. immediately cause the flat surface 52of an axial groove 5| toexert an outward force at B in Figure 17 and inthe direction of the arrow B, thereby urging and wedging the locking andtrailing end of the floating thread member 54 against the threadsof thefemale element. At the same time, because re- 40 striction 59 is bearingon the inner surface of member 54, the restriction 59 will move evenmore closelyagainst the inner surface of the member 54 to apply apressure acting to bend the locking member outwardly. As a result ofthese forces which act instantly upon any unthreading move-. ment of thecap screw, back-lash and the possii-bility of unthreading by vibrationare eliminated.

It is.also-to be noted that when the above forces areapplied, astraightening out tendency is applied to the entire member 54 as hasbeen sions used in an element of a given size and torque required andthat the invention is applicable to threaded elements. of all sizes.Furthermore, the dimensions stated for the .75 cap screws underdiscussion may be varied for even a screw .of such size according to theconditions under whi-ch the invention is to be used.

4 It will be clear that the invention i applicable to threaded elementsof numerous types other than cap screws.

"The terminology used in the specification is for the purpose ofdescription, the scope of the inventlonbeing indicated in the claims.

Iclaim: I

1. In a self-locking threaded device, a threaded element including ahelical groove having a pitch substantially, corresponding to the pitchof its threads, a substantially helical member mounted in the groove, atleast a portion of said member normally being of a diflferent radiusfrom the radius of the thread of said element, said hell-cal memberbeing bodily resilient to bend and thereby conform to a companionthreaded element engaged by said first element, but being sufficientlyrigid that it will exert radial pressure upon the companion element-toresist turning movement pointed out above in connection with the otherforms disclosed herein. Therefore, member 54 will be urgedoutwardly'againstthe threads of the female element.

However, upon the application of suitable force to the cap screw, therestriction 59 can be moved in the direction of the arrow A and beneaththe One such advantage arises from the fact that the points of thelocking ring on which manufacturing tolerances must be closely observedare all with respect to the latter, and coactine. means respectivelycarried by said' threaded element at the trailing end of the helicalgroove and at the trailing end of said helical member whereby the latterwill be more strongly urged into contact with a companion threadedelement upon unthreading movement of said first threaded elewithin asmall area of the locking ring. Thesef tolerances involve only thelength of the flat; portion BI, and the extent to which it is oil'setwith respect to the adjacent curved portion of the member. Thesetolerances are not: dimcult to maintain.- It will be noted that thedistance be--.' tween the two ends of the member 54, or, stated 4. Aself-locking threaded device of the character described in claim 1wherein the greatest radiu of" said helical member is greater than. themajor radius of said threaded element.

5. In a self-locking threaded device, a threaded element including ahelical groove having a pitch substantially corresponding to the pitchof its threads, a substantially helical member mounted in-the groovaathreadon said helical member a ,2,86'i',62'9v of different radialsectionthan the thread of said elements, at least a portion of saidmember normally being of a diflerent radius from the radius of thethread of said element, said helical engaged by said first element butbeing .sufflmember being bodily resilient to bend and there- .by conformto a companion threaded element ciently .rigid that it'will-exertir'adial pressure upon the companion element to resistturning helical member adapted to engage upon unthreading of said firstelement with respect to a companion threaded element.

- 7 6. In a self-locking threaded device, a threaded element including ahelical groove having a pitch substantially corresponding to the pitchof its 7 [10. In a self-docking threaded device, a threaded elementincluding a helical groovehavinga 'pitch substantially corresponding tothe pitch of said member including a portion at, its trailing itsthreads, the trailing end of said groove ter.-Q minating in asubstantially radially. extending shoulder, a radial projection adjacentthe trail- 1 mg end of said groove, a helical member mounted in thegroove and of less length than the latter,

end adapted to engage the groove restriction upon unthreading movementof the threaded element with respect to a companion threaded element. 1

' 11. Ina self-locking threaded device, a threaded element including ahelical groove having a pitchsubstantially corresponding to the pitch-of1 its threads, the trailing end of the groove terthreads, the groovehaving a restrictionat its trailing end, a substantially helical membermounted in the groove, at least a portion of said.

lnember normally having a pitch diameter dif ferent from. the pitchdiameter of. the thread of said element, said member being bodily:resilient to bend and thereby conform to a companion threadedelementengagcd by said firstelement, but being sufliciently rigid thatit will exert radial pressure upon the companion element to stronglyresist turning movement with respect to'the' latter, said helical memberbeing.

its trailing end to engage the restrictiomin the of said first elementwith respect to a companion threaded element:

7 provided with an inwardly deflected portion at groove of said firstelement upon unthreading 7. In a self-locking-threaded device athreadedmally having a pitch diameter different from the pitch diameter ofthe thread ofsaid element,

thereby conform to a companionthreaded ,ele-- ment engaged by said firstelement, but being minatin-g in a substantially radially extendingshoulder, a radial project-ion adjacent the trailing end of said groove,a helical'member mounted in said groove and of a length less than thelength. of the groove, said member having its the companion threadedelement. 1

12. In a self-locking threaded device,a threaded element includinga'helical-groove having a element-including a helical groove h'avingfl-Pitch -swbstantially correspondingiio the pitch of its threads, thegroove having a'restricton therein, fa substantially helical membermounted in the groove; at least a portion of said member-norsufficientlyrigid that it will exert radial pres-L *sure upon the companion element'to strongly ter. said groove restriction being adapted to engage saidmember upon unthreading of said resist turning movement with respect tothe, lat "5o first elem t with respect to a companion thread ed elem nt,the greatest diameter of said helica member. being lessthan the majordiameter of.

said first-named threaded element.

a. In ase'lf-locking threaded device, a threaded substantiallycorresponding to .the pitch of its element including a helical groovehaving a'pitch pitch substantially corresponding to the pitch of itsthreads, the groove having a restriction therein, asymmetricalsubstantially helical member. mounted in the groove, said memberextending.

through approximately 335 and having an outside radius throughoutsubstantially 180 which is greater than the greatest opposed diameter ofa companion threaded elementso that said memher will not turn respect to'a companion fthreaded element upon vibration, and cooperating meansin-the groove and upon the remain ing portion 01 the len thof saidmember adapted "to engage and further urge said member into lockingrelation wit .a companion .threaded 'e 1e, ment upon unthreadingmovement of said grooved element with respect to the com-panion threadedelement.

13. -In a self-locking threaded device, a threaded element includingahelical groove having a pitch substantially corresponding to the pitchof. its threads, the groove having a restriction therein, a symmetricalsubstantially helical member 'mounted in the groove, said memberextending through approi'iimately 335 and having an out- 0 side .radius'throughout substantially 180?- which is greater thanthe greatest opposedradius of .a

companion threaded element, the'remainder of the length of said memberghaving a radius less than the greatest opposed diameter of acompaniongroove; said member including end portions bent inwardly out of thehelix, said groove restriction being adapted to engage one of said bentportiorrs upnn unthreading of said e em nt with respect to a companionthreaded element. I

9. In a se f-locking -threaded device. a threaded element includin ahelical groove havin a pitch substantially corresponding tothe pitch ofits threaded element, and coacting enlargements on the last mentionedportionpf said member and in the groove adaptedto come into contact uponunthreading movement. of said threaded elementwith respect to acompanion threaded element to urge said portion ofsmall radius-intocontact threads a helical groove of 'a pitch substantially correspondingto the pitch of its threads, a subthreads; the groovehaving an outwardlynro- .iectin-g restriction therein at its trailing end a substantiallyhelical member mounted in the groove, said member having an inwardlydeflected portion on its trailing end adapted to enga e the restriction,upon unthreading of said element with respect to a companion threadedelement with the companion element.

14. A self-locking screw having; within its stantially'helical membermounted in said groove, said helical member'beng of less length than thegroove and being fr ely movable lengthwise of the groove, said helicalmember having portions curved on. radii of differentlengths, the radius'ofcurvature of .the central portion of said-member providing anarcsubst'antially concentric in respect to the screw and the radius ofcurvature of the end portions of said member providingan arc eccentricin respect to the screw.

15. A self-locking screw having within its threads a helical groove of apitch substantially corresponding to the pitch of its threads, asubstantially helical member mounted in said groove,

said helical "member being of less length than the groove and beingfreely movable lengthwise of the groove, said helical member havingportions curved on radii of different -lengths, the radius of curvatureof the central portion of said member providing an are substantiallyconcentric in respect to the screw and the radiusof curvature of the endportions of said'member providing threads, said element including a flatsurface at the trailing end of the groove lying ina plane substantiallyparallel to a diameter of the an arc eccentric in respect to the screw,and the.

outside diameter of an appreciable portion of said member beingsufiioiently greater than the outside diameter of the threads of saidscrew to'take up all play between the screw and 'a' companion femaleelement, such as a nut.

threaded e1e'ment,a substantially helical member mounted in the groove,said member including i ment, the groove having a restriction thereinad- 16. In a self-locking threaded device, atnr aded element including ahelical groove having a pitch substantially corresponding to the pitcliof its threads the groove extending through substantially 360, a radialenlargement adjacent but spaced from the trailing end of the groove,both ends of the groove terminating in substantially radially extendingshoulders, a substantially hel-- ical and bodily resilient membermounted in the groove, said member extending through approximately 335throughout substantiallyl80 and in its central portion which is normallygreater than-the greatest opposed 'diameterof a companion threadedelement so that said member will not turn with respect to acompanionthreaded element upon vibration, the trailing end of saidmember being adapted to abut against the trailing end of said grooveduring threading movement of said grooved element with respect to acompanion threaded element, said member being provided with inwardlycurved resilient portions at both ends jacent the flat surface, asubstantially helical member mounted in the groove, said memberincluding an end portion bent out of the helix to lie straight and bearupon the fiat grooved surface in locked position with respect to acompanion. threaded element.

22. In a self-locking threaded device, a threaded element including ahelical groove having a pitch substantially corresponding to the pitchof its threads, said element including a flat surface at and having an.outside radius;

the trailing end of the helical groove lying in a plane substantiallyparallel to a diameter'of the ..ber including an end portion bent out ofthe helix to lie straight and bear upon the flat grooved surthereof, therestriction in the groove being adapted to move beneath the inwardlycurved portion at the trailing end of said member upon unthreadingmovement with respect toa companion element and to thereby force saidtrailing' end outwardly into closer engagement with element; including ahelical groove-having a pitch substantially corresponding tothe pitch ofits threads, said element including a flat surface at one end of thegroove lying in a plane substantially parallel to a diameter of thethreaded element, a substantially helical member mounted in the groove,said member including an inwardly deflected end portion to bear upon theflat grooved surface in locked position with respect to a companionthreaded element.

18. A self-lockingthreaded device of the character described in claim 17wherein the inwardly deflected portion of said helical member isstraight. j t 19. In a self-locking threaded device, a. threaded elementincluding a, helical groove having a pitch substantially correspondingto the pitch'of its face in locked position with respectto acompanionthreaded element.

23. In aself-locking threaded device, athreaded element including ahelical groove having a pitch substantially corresponding to the pitchof its threads, a substantially helical member mounted in the groove, atleast a portion of said member normally being of different radius fromthe radius of the thread of said element, said helical member beingbodily resilient to bend and thereby conform to a companion threadedelement engaged by said first element, but being sufliciently rigid thatit will exert radialpressure upon the companion element to resistturning movement with respect to the latter, and coacting means carriedby said threaded element and said helical member whereby the latter willbe more strongly urged into contact witha companion threaded elementupon unthreading ofsaid first threaded element with respect to acompanion threaded element, said helical member'having a thread of lessthan standard depth, but which is otherwise of the same transversesection as "the thread of said first named threaded element.

24. A'self-locking threaded device of the characteridescribed in claim 8wherein said helical member is provided with a thread of the samesection as that of said threaded element and the greatest radius of saidhelical member is less than the major radius of said threaded element.25. A self-locking threaded device of the character described in claim 8wherein said helical member is'provided with a thread which istruncatedin radial section.

26. A self-locking threaded device of the character described in claim 5wherein said helical member is provided with a thread which is truncatedin radial section. i

. CLARENCE W. SOLDAN.

